1. Field of the Invention
The present invention is concerned with the structure and mounting of a mining bit of the type which comprises a cylindrical shank and a pointed working head adapted to be carried on the periphery of a mining machine wheel.
2. Description of the Prior Art
Mining machine bits having supporting shanks and operating heads of a generally conical shape with the apex of the head comprising an axially disposed point of a hard metallic carbide are known. They are generally utilized in mining machines having power driven cutter wheels. In these machines the power driven wheel is mounted on a horizontal shaft with the plane of the wheel disposed in a vertical plane. The wheel has on its periphery an array of cutter bits mounted on the rim of a wheel carried on a horizontal shaft, generally maintained in a horizontal position. The wheel comprises, on its periphery, a plurality of permanent mounting sockets adapted to hold pointed carbide tipped cutter bits which are mounted substantially tangentially on the peripheral rim of the supporting wheel so that through the rotation of the wheel about it's axis the bits may attack the material to be broken up by the horizontal reach of the teeth or cutter bits operating in a vertical plane.
In the course of operation of the machine, these bits engage and break up the surface in which they come in contact. Such machines are utilized in mining geological formations and in reducing large mineral deposits into pieces suitable for purpose and other similar applications.
While the machines are in operation, it is beneficial that the bits rotate freely in the sockets. This allows the wear upon the bit and the carbon insert to be distributed evenly allowing the bit to retain its symmetry thereby providing continuous sharpness of the bit and carbon insert in operation.
It is readily apparent that due to the nature of the work which the machine performs, the stresses on the machine are high and irregular. In addition, while the wear on the cutting portion of the bit is evenly incurred by allowing rotation of the bit, such rotation results in interaction between the bit and mount.
As a consequence of the foregoing the wearing down of the stem or shank of the bits, those portions within the mounts, and the mounts themselves becomes inevitable. This necessitates frequent replacement of the bits and eventually the mounts to maintain the efficiency of the machine.
Such replacement increases the expense of operating the machine due to the actual replacement of the worn parts and labor involved, but also due to the down time, or inoperability of the machine during such replacement.